1. Field of Invention
The present invention relates to an optimum power calibration method, and more particularly to an optimum power calibration method applied to a rewritable optical disk drive.
2. Related Art
For rewritable optical disks, such as CD-RW, DVD-RW and DVD+RW, one first performs an optimum power calibration (OPC) procedure in a power calibration area of the rewritable optical disk to determine the writing power of an optical pick-up head for writing data to the optical disk.
FIG. 1 shows the relationship between the number of times of writing a conventional rewritable optical disk on the horizontal axis, and the corresponding rate of data reading failure frequency on the vertical axis. When an empty rewritable optical disk is written with data several times, the corresponding rate of data reading failure frequency of the written data may be different. In particular, it is more likely to cause reading failure at the first few times of writing the rewritable optical disk. For a CD-RW, one can observe its C1 and C2 values to evaluate the reading failure frequency. For a DVD-RW, one can observe its PI and PO values to evaluate the rate of data reading failure frequency.
However, the higher the rate of the reading failure frequency is, the more difficult it is for the optical disk drive to correctly read the written data on the optical disk. The worst case is that the written data recorded on the rewritable optical disk may have been lost already.
One of possible reasons for the reading failure of written data on the rewritable optical disk may be that the optimum power calibration procedure before the data writing is not optimized. In that case, the written data are not correctly recorded on the rewritable optical disk and, therefore, it is likely to encounter failure when reading the written data.
It is thus imperative to provide an optimum power calibration method and an optical disk drive. It is expected to find an appropriate writing power by improving the current optimum power calibration procedure. It is also expected to improve the reading failure during the first few times of data writing.